Siemens Aktiengesellschaft

Holger Adolf

Rene Gumbrecht

Thomas Benner

Hans-Peter Fautz

Jörg Ulrich Fontius

Joerg Ulrich Fontius

Matthias Gebhardt

Franz Schmitt

Nikolaus Demharter

Rudi Baumgartl

In order to reduce the memory footprint used for monitoring specific absorption rate (SAR) in a magnetic resonance imaging (MRI) system, a hybrid sliding window method is provided. The method includes receiving a measured value once every first time interval, processing the measured value, and storing a value resulting from the processing in a first memory element. Measured values stored in second memory elements are summed every second time interval, where the first time interval is less than the second time interval. A representation of SAR is calculated every first time interval based on the value resulting from the processing and the sum of the measured values of the second memory elements. When the second time interval is reached, the value stored in the first memory element is moved to one of the second memory elements, and the value stored in the first memory element is reset to zero.

Hybrid averaging method for specific absorption rate supervision

A method for operating a transmission device of a magnetic resonance device is provided. In order to actuate coil elements of a radiofrequency coil with different phases, phase differences in a reference plane are taken into consideration. In a first calibration measurement to be performed once for each transmission path, a first phase of a transmitted radiofrequency signal is measured by an internal measuring device installed permanently in the transmission device spaced apart from the reference plane. A second phase of the transmitted radiofrequency signal is measured by a second, external measuring device to be connected to the reference plane for the first calibration measurement. At least one phase of the first phase and the second phase is taken into consideration in the phase-accurate actuating of the coil elements and/or for correcting further measurements with the internal measuring device.

Operation of a transmission device of a magnetic resonance device

A circuit arrangement for driving a transmission coil arrangement with at least two individual transmission coils of a magnetic resonance system for supplying a radiofrequency signal for producing alternating electromagnetic fields over at least two channels, with in each case a digital section and an analog section, is provided. In the digital section, in an envelope generator, base frequency signals that respectively generate an envelope are provided. The circuit arrangement also includes an intermediate frequency oscillator that generates a common intermediate frequency, a frequency mixer per channel for mixing the common intermediate frequency into the base frequency signals, and in the analog sections of the channels, respectively, second frequency mixers that mix a common radiofrequency signal into each base frequency signal. The envelope is transmitted, with the mixed-in intermediate frequency signal, and the total signal thus obtained is respectively conducted to an individual transmission coil via a respective amplifier.

Circuit arrangement for the driving electronics of a magnetic resonance system

Methods are provided for measurement of RF excitation pulses by a magnetic resonance device. The methods include the following acts: (1) sending of an RF excitation pulse by a radio-frequency system of the magnetic resonance device, (2) triggering of a receive event for capturing the RF excitation pulse by the control device of the magnetic resonance device, and (3) capturing of the sent RF excitation pulse in the form of excitation data by the radio frequency system. The excitation data may be used for checking process execution sequences.

Measurement of radio frequency excitation pulses

In a computer-implemented method, device and system for controlling an imaging system, a specific absorption rate is calculated with a computation unit and an RF transmission signal of the imaging system is controlled with a control device. The process of controlling of the RF transmission signal includes disconnecting the RF transmission signal when a remaining period during which the RF transmission signal is harmless for the patient has been reduced to zero.

Device, method and system for controlling imaging methods and systems

In order to provide online monitoring of local specific absorption rate (SAR) within a body subject to a magnetic resonance imaging (MRI) scan, directional couplers measure a phase and an amplitude of a transmission radio frequency (RF) pulse generated and transmitted by an MRI system. A measured local SAR value is calculated based on the measured phase and the measured amplitude of the transmission RF pulse using a voxel model of the body and an electromagnetic (EM) simulation. In order to verify proper operation of the local SAR monitoring, the measured local SAR value is compared to a predetermined local SAR value.

Safety tests for systems monitoring local SAR

In order to configure a transmission coil of a magnetic resonance imaging (MRI) system without taking a specific measurement object into account, the transmission coil is automatically detected and identified when the transmission coil is connected to the MRI system. A phase setting of a pulse to be transmitted by the detected transmission coil is identified based on at least the identified type of the transmission coil. The transmission coil is excited with the pulse having the identified phase and amplitude.

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Zirndorf, Germany

Holger Adolf